Oscillatory system for a motorized drive unit

ABSTRACT

An oscillatory system for a motorized drive unit for the generation of a rotary oscillatory movement is provided. The system includes a first oscillatory component and a second oscillatory component, the components capable of oscillating relative to one another around an axis of oscillation; and at least two elongate spring elements, each spring element having a first fastening point and a second fastening point spaced apart from one another. The spring elements are elastic in the direction of the rotary oscillatory movement. For each spring element the first fastening point is connected to the first oscillatory component and the second fastening point is connected to the second oscillatory component such that the spring elements intersect at the axis of oscillation, the axis of oscillation having an angle of intersection different from 0 degrees.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of European Patent ConventionApplication No. 09 006 043.5, filed on May 2, 2009, the substance ofwhich is incorporated herein by reference.

FIELD OF THE INVENTION

The present disclosure relates generally to an oscillatory system for amotorized drive unit for the generation of a rotary oscillatorymovement. The present disclosure also relates to an oscillatory systemhaving a first component and a second component able to oscillaterelative to one another around an axis of oscillation, and moreparticularly to a small electric appliance having an oscillatory systemhaving a motorized drive unit that includes an electromagnetic driveelement.

BACKGROUND OF THE INVENTION

Oscillatory systems are used in direct drives which can carry outmovements without any further mechanical transmission elements. It is,for example, desirable in the drive of electric toothbrushes to generatea rotary oscillatory movement around a drive shaft axis and, inaddition, a translatory oscillatory movement, for example, a radialmovement. For this purpose, the drive represents an oscillatory systemwhich can oscillate in a plurality of degrees of freedom. The journalingof the two components able to oscillate with respect to one another isrealized in this respect by ball bearings, for example.

A drive unit which can generate a movement having a plurality of degreesof freedom, of which one in particular is a rotary oscillatory movement,is described in WO 2005/062445 A1.

It is desirable to set forth an oscillatory system for a motorized driveunit for the generation of a relative rotary oscillatory movement, saidoscillatory system realizing a journaling and spring function in asimple manner and enabling a compact structure of a motorized driveunit. Accordingly, there is a need for an oscillatory system having thefeatures described herein.

SUMMARY OF THE INVENTION

In one embodiment, an oscillatory system for a motorized drive unit forthe generation of a rotary oscillatory movement includes a firstoscillatory component and a second oscillatory component, the componentscapable of oscillating relative to one another around an axis ofoscillation; and at least two elongate spring elements, each springelement having a first fastening point and a second fastening pointspaced apart from one another. The spring elements are elastic in thedirection of the rotary oscillatory movement. For each spring elementthe first fastening point is connected to the first oscillatorycomponent and the second fastening point is connected to the secondoscillatory component such that the spring elements intersect at theaxis of oscillation, the axis of oscillation having an angle ofintersection different from 0 degrees.

In another embodiment, a motorized drive unit for the generation of arotary oscillatory movement includes an electromagnetic drive elementhaving an output axle; and an oscillatory system. The oscillatory systemincludes a first oscillatory component and a second oscillatorycomponent, the components capable of oscillating relative to one anotheraround an axis of oscillation; and at least two elongate springelements, each spring element having a first fastening point and asecond fastening point spaced apart from one another. The springelements are elastic in the direction of the rotary oscillatorymovement. For each spring element the first fastening point is connectedto the first oscillatory component and the second fastening point isconnected to the second oscillatory component such that the springelements intersect at the axis of oscillation, the axis of oscillationhaving an angle of intersection different from 0 degrees. A firstoscillatory component is rotationally fixed to the electromagnetic driveelement and the second oscillatory component is connected to the outputaxle.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims which particularly pointout and distinctly claim the subject matter that is regarded as theinvention, it is believed the various embodiments will be betterunderstood from the following description taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a perspective and partly open view of an electric toothbrushwith an oscillatory system in accordance with one embodiment;

FIG. 2 is another perspective view of the electric toothbrush of FIG. 1;

FIG. 3 is a plan view taken along line DI of FIG. 2;

FIG. 4 a is a plan view of an oscillatory system in accordance with oneembodiment;

FIG. 4 b is a perspective view of the oscillatory system of FIG. 4 a;

FIG. 5 a is a perspective view of an oscillatory system in accordancewith another embodiment;

FIG. 5 b is a perspective view of the oscillatory system of FIG. 5 athat has been overmolded;

FIG. 6 a is a plan view of an oscillatory system in accordance withanother embodiment;

FIG. 6 b is a perspective view of the oscillatory system of FIG. 6 a;

FIG. 7 a is a perspective view of an oscillatory system in accordancewith another embodiment;

FIG. 7 b is an end view taken along line VII b of FIG. 7 a;

FIG. 7 c is a side view of the oscillatory system taken along line VII cof FIG. 7 a, showing a first operating state;

FIG. 7 d is a side view of the oscillatory system taken along line VII cof FIG. 7 a, showing a second operating state;

FIG. 8 a is a perspective view of an oscillatory system in accordancewith another embodiment;

FIG. 8 b is a side view of the oscillatory system taken along line VII bof FIG. 8 a;

FIG. 9 is a perspective and partly open view of an electric toothbrushwith an oscillatory system in accordance with another embodiment; and

FIG. 10 is a cross-sectional view taken along line X-X of FIG. 9. Thefigures herein are not necessarily drawn to scale.

DETAILED DESCRIPTION OF THE INVENTION

According to the present disclosure, an oscillatory system includes amotorized drive unit for the generation of a rotary oscillatorycondition. In one embodiment, the drive unit includes a first componentand a second component which can oscillate relative to one anotheraround an axis of oscillation and which carry out a relative rotaryoscillatory movement with respect to one another. As described herein,the oscillatory system may include at least two elongate spring elementswhich are elastic at least in the direction of the rotary oscillatorymovement. Each of these spring elements has two fastening points spacedapart from one another in each case. One of these fastening points isrespectively connected to the first oscillatory component and the otherfastening point is connected to the second oscillatory component. Thespring elements therefore connect the first oscillatory component andthe second oscillatory component to one another, but permit a rotaryoscillatory movement due to their elasticity in its direction.

The at least two elongate spring elements are arranged such that theconnection line of the fastening points of a first spring element andthe connection line of the fastening points of a second spring elementcross at an angle of intersection which is different from 0°. The twooscillatory components are fixedly connected to one another in thismanner. Due to the elasticity of the spring elements, however, arelative rotary oscillatory movement is possible around the point ofintersection of the connection lines of the respective fastening points.

The spring arrangement formed in this manner allows both the journalingand the spring function of two oscillatory components relative to oneanother which can be realized with relatively simple components. Otherjournaling elements such as ball bearings or slide bearings may beeliminated so that the oscillatory system in accordance with the presentdisclosure ensures a very cost-effective structure. In one embodiment,the spring elements may intersect in the axis of oscillation. Inparticular the virtual axis of intersection formed by the intersectedspring angle is collinear to a drive axle which is rotationally drivenby a motor to generate the rotary oscillatory movement.

In one embodiment, movement of the spring elements in a translatorydirection radially to the axis of oscillation is also possible. Thismovement may be accomplished with a setting of the respectiveoscillatory properties, in particular of the frequency and of theamplitude, being possible in a simple manner by a suitable selection ofmaterials and shape of the spring elements. In another embodiment, thespring elements include leaf springs whose leaf spring surfaces areparallel to a respective plane which includes the axis of oscillation.Leaf springs are simple to manufacture and provide the elasticity aroundan axis which is disposed in its leaf spring surface with asimultaneously higher stiffness in other spatial directions. The leafsprings may be made of any suitable material, including, for example,sheet metal. A cost-effective embodiment provides that the leaf springsof the system are bent from a common sheet metal part so that only apunching process is required.

The first and the second oscillatory components may be made of anysuitable material, including, for example, plastic. In one embodiment,the plastic components may be made as injection molded plastic parts. Itis then possible in a simple manner to overmold the spring elements withthese plastic parts during the manufacturing process so that the firstand the second oscillatory components and the spring elements arealready fixedly connected to one another in the injection process. Thisis particularly advantageous if the spring elements include leaf springswhich are bent from a common sheet metal part. In this manner, a compactand fixed unit is created of oscillatory components and spring elements.In another embodiment, the entire oscillatory system may be manufacturedfrom plastic parts resulting in lower manufacturing costs.

The stiffness of the oscillatory system in different spatial directionscan be set differently by selection of the angle of intersection betweenthe spring elements. If the angle of intersection amounts to 90°, forexample, the stiffness for a translatory movement with otherwise equalproperties of the two spring elements in a direction transverse to theaxis of oscillation and from one oscillatory component to the other isthe same as the stiffness in the direction perpendicular thereto, withthe angle of intersection between a part of a first spring element whichis connected to the first oscillatory component and a part of a secondspring element which is connected to the second oscillatory componentbeing measured. The system then substantially represents a rotarybearing.

If, in contrast, an angle of intersection is selected which is not equalto 90°, the stiffness values in different transverse directions to theaxis of oscillation can be selected at different levels. If, forexample, an angle of intersection is selected which is less than 90°,the system is softer in a direction from the first oscillatory componentto the second oscillatory component than in a direction perpendicularthereto. Alternatively or additionally to the selection of an angle ofintersection differing from 90°, a different oscillatory capability canbe achieved in different directions by a suitable profiling of thespring elements.

In one embodiment, spring elements may also be elastic in a directionparallel to the axis of oscillation. In this manner, an axialoscillatory movement can also be generated. The spring elements can forthis purpose be selected, for example, such that they have comparableelasticity in all directions. A realization which is simple tomanufacture and is reliable provides that leaf springs which have a mainleaf spring surface including the axis of oscillation are also used forsuch an embodiment. The ends of the leaf springs in the vicinity of thefastening points are, however, in one embodiment, bent by approximately90° so that there is also increased elasticity in the direction of theaxis of oscillation in this region. If a plurality of such leaf springsare arranged next to one another, an almost linear movement is possibleparallel to the axis of oscillation in this manner so that a linearbearing is realized.

The total oscillatory system can in turn be suspended in an oscillatorymanner, for, example in a housing. In this embodiment, similarintersected spring arrangements, which include leaf springs, forexample, can be used as for the oscillatory system itself. On acorresponding embodiment of these springs made as suspension elements,the first oscillatory component then oscillates in phase opposition tothe second oscillatory component. For example, the suspension elementscan be arranged substantially parallel to the spring elements. Use of anembodiment in which an oscillatory component is fastened in the housingof an electric toothbrush, will considerably reduce the oscillationswhich can be felt at the hand piece.

In one embodiment, a drive unit has an electromagnetic drive element andan oscillatory system. In one example, the electromagnetic drive elementis in the form of an electric motor. One of the oscillatory componentsof the oscillatory system is rotationally fixedly connected to theelectromagnetic drive element and the other oscillatory component isconnected to the drive axle of the electromagnetic drive element.

In another embodiment, an electromagnetic drive element is used whichprovides a rotary oscillatory movement and a translatory oscillatorymovement. Such a drive unit with an electromagnetic drive element isparticularly suitable for the drive of a small electric appliance sincea compact and simple structure is possible. Such small electricappliances which can be driven by a drive unit may include electricrazors and electric toothbrushes, for example, in which a rotaryoscillatory movement is frequently combined with a translatoryoscillation movement. In one embodiment, a drive unit for an electrictoothbrush will have the brush head being connected to one of theoscillatory components of the oscillatory system, for example, to theoscillatory component which is connected to the drive axle of theelectromagnetic drive element.

An electric toothbrush 10, with the housing forming the handle beingopen is shown in FIG. 1. An electromagnetic drive element 14 isconnected to a battery 16 for the power feed. The electromagnetic driveelement and the battery are fastened to a chassis 18. A firstoscillatory component forming an oscillator 26 is connected to theoutput of the electromagnetic drive element. Leaf spring elements 28, 30connect the oscillator 26 to the chassis 18 which in this respect formsthe second oscillatory component. A rotary output force is provided bythe electromagnetic drive element 14 which results in a relative rotaryoscillatory movement in the direction A between the chassis 18 and theoscillator 26. The leaf springs 28 intersect with the leaf spring 30 inthe axis of oscillation 32 around which this rotary oscillatory movementtakes place.

The electromagnetic drive element 14 is made such that it canadditionally stimulate a translatory oscillatory movement in thedirection B which can be passed on by the oscillatory system 12 in amanner described herein. The movement of the oscillator 26 is passed onvia the output axle 22 of the oscillatory system 12 to the pushed-onbrush head 20 which in this respect carries out a rotary oscillatorymovement in direction A and a translatory oscillatory movement indirection B. A circuit board 24 is provided beneath the chassis 28.

As shown in FIG. 2, power feeds 34 are visible which connect theelectromagnetic drive element 14 to a battery (not shown). The electrictoothbrush 10 is shown without the pushed on brush head 20. Thefastening points 36, 38 of the leaf springs 28, 30 at the chassis 18 arefurther shown in FIG. 2.

FIG. 3 depicts a partly transparently shown plan view of the embodimentof FIGS. 1 and 2 in the direction of view III, such as is set forth inFIG. 2. Here, the fastening points 40, 42 of the leaf springs 28, 30 atthe oscillator 26 are additionally shown.

FIG. 4 depicts a schematic representation of an oscillatory system suchas it can be used in this embodiment. Whereas FIG. 4 a shows a schematicplan view in the direction of the pivot axis, FIG. 4 b is acorresponding perspective representation. For reasons of clarity,however, only two spring elements 28, 30 are shown here. a designatestheir angle of intersection. As can in particular be recognized in FIG.4 a, the leaf springs 28, 30 intersect in the pivot axis which, on theother hand, is colinear or parallel to the output axle 22 of theelectromagnetic drive element.

With respect to the embodiment shown in FIGS. 1 to 4, theelectromagnetic drive element 14 generates a rotary oscillatory movementof the oscillator 26. A rotary oscillation around the axis ofoscillation 32 is possible due to the cross-wise arrangement of the leafsprings 28, 30. The leaf spring design of the crossed springs 28, 30additionally enables a translatory oscillatory movement in direction B,for example. This results in a very high stiffness being given due tothe cross-wise arrangement of the springs. If the electromagnetic driveelement 14 additionally provides such a linear oscillatory movement, theoscillator 26 moves, on the one hand, relative to the chassis 18 aroundthe axis of oscillation 32 and, on the other hand, carries out apulsation movement in the direction B. By a suitable choice of thematerial of the springs 28, 30, their stiffness and thus the oscillatoryamplitude and resonant frequency of the respective oscillation can beset to the desired degree and can optionally be selectively excited.

In the embodiment of FIG. 4, an oscillatory system is shown in which theleaf springs 28, 30 intersect at an angle α amounting to 90°. Thestiffness in the linear direction B and in the linear direction C isaccordingly comparable. If the angle α is selected to be less than 90°,for example 60°, the stiffness is reduced in direction B with respect tothe stiffness in the direction C. In this way, the resonant frequenciesof the oscillations can also be set differently in different directionsand can, for example, preferably trigger the desired oscillatory mannerby excitation of the respective resonant frequency.

FIG. 5 a shows a detail of the embodiment of FIGS. 1 to 4. Inparticular, a bent sheet metal part 48 is visible which is bent in onepiece to form the leaf springs 28, 30. In this respect, the leaf springs28, 30 are connected to one another via the chassis fastening 54 bywhich the bent sheet metal part 48 can be screwed, for example, to thechassis 18. A connection element 52 is, for example, fixedly connectedto the part of the leaf spring 30 at the top in FIG. 5 a. An enclosurefor the output axle 22 of the oscillator 26 is indicated by referencenumeral 50, whereas reference numeral 56 indicates a motor couplingelement to the output of the electromagnetic drive element 14. The partof the bent sheet metal part 48 at the top in FIG. 5 a which includesthe connection element 52 and the upper parts of the spring elements 28,30 is overmolded in the injection molding process by which theoscillator 26 is formed as a plastic part. In this manner, the bentsheet metal part 48 is fixedly connected to the oscillator 26 and/or tothe chassis 18, as is shown in FIG. 5 b.

FIG. 6 depicts another embodiment of an oscillatory system. The leafsprings 44, 46 are here not made straight, but have a profiling 45, 47.The axis of oscillation 32 is furthermore located at the point ofintersection of two imaginary lines between the fastening points 36, 40,on the one hand, and the fastening points 38, 42, on the other hand.However, the stiffness here is in particular reduced in the direction Bdue to the profiling 45, 47.

Another embodiment of an oscillatory system is shown in FIG. 7. Thesystem as shown in FIG. 7 allows for an additional translatoryoscillatory movement in direction D. In this embodiment, the springelements 60, 62 are not made as leaf springs, but as rod springs whichhave an elasticity around the axis of oscillation 32 and in the axialdirection D. The use of three leaf springs 60, 62 enables an almostlinear movement in the direction D parallel to the axis of oscillation32, as is indicated in FIG. 7 d, which shows the same direction of viewto this embodiment as FIG. 7 c, only in a different operating state inwhich the oscillator 26 and the chassis 18 are displaced in thedirection D with respect to one another. If accordingly a linearoscillatory movement along the axis of oscillation 32 is provided by theelectromagnetic drive element 14 in addition to the rotary oscillatorymovement in the direction A around the axis of oscillation 32 in such anembodiment, the rotary oscillatory movement A can be combined with alinear oscillation in the axial direction D.

FIG. 8 shows another embodiment of the system of FIG. 7. The springelements are made as leaf springs 64, 66, with the main leaf springsurface including the axis of oscillation 32. The ends 68, 70 of theleaf springs 64, 66 are, however, bent by 90° in the region of thefastening points to the chassis 18 or to the oscillator 26. In theregion of the ends 68, 70 of the leaf springs, a respective bendingplane 72 is defined in this manner which are shown in dotted line formin FIG. 8 b. A reduced stiffness in the direction D is given in theregion of the ends 68, 70 of the leaf springs so that the linearmovement becomes possible in this direction, as is shown in FIG. 8 b.The individual embodiments can naturally also be combined so that, forexample, by a suitable choice of the angle of intersection between theleaf springs 64, 66 in the embodiment of FIG. 8, the stiffness in thedirection B is reduced with respect to the stiffness in the direction Cso that a translatory oscillatory movement in the direction B can becombined with an axial oscillatory movement in the direction D and arotary oscillatory movement in the direction A when the electromagneticdrive element 14 stimulates corresponding movements.

FIGS. 9 and 10 show embodiments of an oscillatory system 12 furthercomprising suspension elements 82. An electromagnetic drive element 14is connected to a battery 16 for the power feed. The chassis 18 isconnected via suspension elements 82 to frame elements 80 which areconnected to the housing of the electric toothbrush not shown in FIG. 9.The suspension elements 82 are in this respect made in the same way asthe spring elements 28, 30 via which the chassis 18 and the oscillator26 are connected to one another in the described manner. The suspensionelements in this embodiment include leaf springs 82 which are arrangedparallel to the spring elements 28, 30. If the electromagnetic driveelement 14 provides a rotary oscillatory movement, the chassis 18oscillates in phase opposition to the oscillator 26 in the direction E.In this manner, in particular with an electric toothbrush, thevibrations onto the housing forming a handle of the electric toothbrushcan be reduced.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm”.

Every document cited herein, including any cross referenced or relatedpatent or application, is hereby incorporated herein by reference in itsentirety unless expressly excluded or otherwise limited. The citation ofany document is not an admission that it is prior art with respect toany invention disclosed or claimed herein or that it alone, or in anycombination with any other reference or references, teaches, suggests ordiscloses any such invention. Further, to the extent that any meaning ordefinition of a term in this document conflicts with any meaning ordefinition of the same term in a document incorporated by reference, themeaning or definition assigned to that term in this document shallgovern.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

1. An oscillatory system for a motorized drive unit for the generationof a rotary oscillatory movement, the system comprising: a firstoscillatory component and a second oscillatory component, the componentscapable of oscillating relative to one another around an axis ofoscillation; and at least two elongate spring elements, each springelement having a first fastening point and a second fastening pointspaced apart from one another, wherein the spring elements are leafsprings having surfaces that are elastic in a direction parallel to theaxis of oscillation; and further wherein for each spring element thefirst fastening point is connected to the first oscillatory componentand the second fastening point is connected to the second oscillatorycomponent such that the spring elements intersect at the axis ofoscillation, the axis of oscillation having an angle of intersectiondifferent from 0 degrees.
 2. The oscillatory system according to claim1, wherein the leaf springs are made of sheet metal.
 3. The oscillatorysystem according to claim 2, wherein the leaf springs are formed from acommon sheet metal part.
 4. The oscillatory system according to claim 1,wherein the first oscillatory component and a second oscillatorycomponent are made of plastic.
 5. The oscillatory system according toclaim 4, wherein the first oscillatory component and a secondoscillatory component are formed as injection molded parts.
 6. Theoscillatory system according to claim
 5. wherein the at least two springelements are partly overmolded with the first and second oscillatorycomponents such that the spring elements and the oscillatory componentsare fixedly connected to one another.
 7. The oscillatory systemaccording to claim 1, wherein the angle of intersection is 90 degrees.8. The oscillatory system according to claim 1, wherein the angle ofintersection is not equal to 90 degrees.
 9. The oscillatory systemaccording to claim 1, wherein the at least two spring elements areprofiled.
 10. The oscillatory system according to claim 1, wherein thesurfaces of the leaf springs are parallel to a respective plane whichincludes the axis of oscillation and further wherein the leaf springsinclude ends that are angled such that the ends are perpendicular to theaxis of oscillation.
 11. A motorized drive unit for the generation of arotary oscillatory movement comprising: an electromagnetic drive elementhaving an output axle; and an oscillatory system, the oscillatory systemincluding a first oscillatory component and a second oscillatorycomponent, the components capable of oscillating relative to one anotheraround an axis of oscillation; and at least two elongate springelements, each spring element having a first fastening point and asecond fastening point spaced apart from one another, wherein the springelements are leaf springs having surfaces that are elastic in adirection parallel to the axis of oscillation; wherein for each springelement the first fastening point is connected to the first oscillatorycomponent and the second fastening point is connected to the secondoscillatory component such that the spring elements intersect at theaxis of oscillation, the axis of oscillation having an angle ofintersection different from 0 degrees; wherein a first oscillatorycomponent is rotationally fixed to the electromagnetic drive element andthe second oscillatory component is connected to the output axle. 12.The motorized drive unit according to claim 11, wherein theelectromagnetic drive element is an electric motor.
 13. A small electricappliance having a motorized drive unit according to claim
 11. 14. Asmall electric appliance according to claim 13, wherein the appliance isan electric toothbrush.
 15. An oscillatory system for a motorized driveunit for the generation of a rotary oscillatory movement, the systemcomprising: a first oscillatory component and a second oscillatorycomponent, the components capable of oscillating relative to one anotheraround an axis of oscillation; at least two elongate spring elements,each spring element having a first fastening point and a secondfastening point spaced apart from one another, wherein the springelements are elastic in the direction of the rotary oscillatory movementand further wherein for each spring element the first fastening point isconnected to the first oscillatory component and the second fasteningpoint is connected to the second oscillatory component such that thespring elements intersect at the axis of oscillation, the axis ofoscillation having an angle of intersection different from 0 degrees;and at least two suspension elements for connecting the secondoscillatory component to a housing frame.